The applicants propose to develop a system of computer software and hardware broadly applicable to problems of stereotaxic neurosurgery. A neurosurgical workstation would provide the surgeon with easy access to data from differing image modalities (e.g., CT, MRI, and PET) to optimize stereotaxic procedures. In contrast to existing systems, the workstation would easily integrate multiple images in a common coordinate system, provide an intuitive and powerful user interface, and display intersections of stereotaxic trajectories with any image plane, allowing the surgeon to simulate multiple surgical approaches. By the end of Phase I, the following goals will have been achieved: 1) evaluation and selection of hardware, 2) specification of the prototype's software, 3) design of the user interface, 4) programming of machine-independent algorithms, and 5) development of safety and accuracy guidelines. Development and testing of a prototype system would be accomplished in Phase II. The proposed stereotaxic neurosurgical system is designed to narrow the gap between current medical imaging technologies and the tools which make these data useful. The modularity of design and the specific attention to use interface should make this system an defective tool in a wide variety of neurosurgical procedures.